1. Field of Use
This invention relates generally to a fastener assembly commonly known as an "expansion rivet" or a "blind rivet" and comprising a hollow plastic expandable rivet insertable into aligned holes in panels and a plastic pin axially movable in the rivet to cause rivet expansion whereby the panels are secured together. In particular, the invention relates to integral flexible sealing means on the rivet to seal the panel holes in which the rivet is mounted.
2. Description of the Prior Art
Fastner assemblies of the aforesaid general character are known and in use., U.S. Patent application Ser. No. 371,652, now U.S. Pat. No. 4,556,351, for "EXPANSION RIVET ASSEMBLY" illustrates the state of the art, as well as an expansion rivet assembly over which the present invention is an improvement. That patent application is assigned to the same assigned or the present application. That patent application discloses an expansion rivet assembly which comprises two separately moloed plastic components, namely: an expandable hollow plastic rivet or female member and a plastic drive pin or male member. The rivet has a head or flange at one end and has a slotted shank insertable in aligned holes or slots in two or more flat sheetlike workpieces to be joined together. The rivet has a bore therethrough and the bore has portions of reduced diameter at opposite ends. The bore portion of reduced diameter near the head end of the rivet is provided with annular grooves. The drive pin has a head at one end and a shank which is extendable through the rivet bore. The drive pin shank has a first cylindrical portion, an adjoining second cylindrical portion of reduced diameter, and a break-away indentation located between the first and second portions. The first portion includes serrations and also a groove adjacent the pin head. The drive pin is adapted to be axially drawn into the bore in the rivet by a tool which engages the second cylindrical portion of the pin shank and which causes the drive pin head to engage the insertion end of the rivet shank and effect outward expansion of the rivet shank wall. Such movement also finally causes break-off of the now-superfluous projecting second cylindrical portion or end of the pin shank at the aforementioned break-away indentation formed in the pin shank. The reduced bore portion near the insertion end of the rivet engages the groove in the pin shank adjacent the pin head to temporarily hold the pin and rivet together prior to use. The serrations in the first portion of the pin shank, which are initially disengaged from the large diameter bore portion of the rivet, engage the grooved bore portion of reduced diameter at the head end of the rivet upon full insertion to hold the pin and rivet together permanently.
The fastener assembly disclosed in U.S. patent application Ser. No. 371,652 firmly and permanently secures two or more panels together in tight relationship and is well-adapted for use, for example, in automobile or domestic appliance construction to secure sheets of material or liners which line the interior of the automobile or appliance to other sheet metal panels or structural members. In some cases the panels are exposed to water or other liquids and there is a risk of liquid leakage through the aligned holes in which the rivet is mounted. If such leakage is undesirable because of possible damage to the panels or to objects near the panels, the hole can be sealed by means of a compressible washer or similar sealing device which is disposed on the rivet shank between the rivet head and the adjacent panel. This solution to the leakage problem requires an additional component and additional labor to install it and results in added costs.